1. FIELD OF THE INVENTION
This invention relates to a semiconductor device or, more particularly, to the structure of a multi-pin semiconductor device having several hundred or more pins.
2. DESCRIPTION OF THE RELATED ART
Semiconductor devices manufactured by using a type of tape carrier called a "TAB (tape automated bonding)" type have been used as low-cost packages with a very large number of pins. FIGS. 1 and 2 show the structure of this type of conventional semiconductor device. FIG. 1 is a plan view of the semiconductor device with an upper resin portion 8 of a package body 7 (refer to FIG. 2) removed. The package body 7 is a part molded with a resin. FIG. 2 is a cross-sectional view taken along line II--II of FIG. 1. A plurality of electrodes 2 formed on a surface of a semiconductor element (semiconductor chip) 1 are electrically connected to inner lead portions 5 of leads 4 formed on an insulating tape 3. The semiconductor element 1 and the inner leads 5 are molded in the package body 7 formed of a resin, while outer lead portions 6 of the leads 4 extend from the package body 7.
During the operation of this semiconductor device, the semiconductor element 1 generates heat, which is conducted to the outside of the semiconductor device through the leads 4 and the package body 7.
In the thus-constructed conventional semiconductor device, the amount of heat generated by the semiconductor element increases as the degree of integration of the semiconductor element is increased. However, the heat generated by the semiconductor element is not efficiently dissipated to the outside of the semiconductor device because the resin which forms the package body is made of an epoxy resin, for example, which has poor thermal conductivity characteristics. The heat therefore remains in the semiconductor device. If the rate at which the semiconductor element generates heat is high, there is a risk of a malfunction of the semiconductor element owing to the elevated temperature, resulting in reduced reliability of the semiconductor device. Moreover, in the case of a multi-pin package, the length of each lead is increased and the inductance of the leads is thereby increased, which results in a deterioration of the electrical characteristics, e.g., an increase in noise and a reduction in the response speed of the semiconductor device. On the other hand, if the package body is formed of a ceramic material which has superior thermal conductivity characteristics, the semiconductor device can be improved in heat dissipating properties and in response speed. However, such a ceramic body is very expensive and increases the manufacture cost of the semiconductor device.